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Recently, the vagus nuclei in the brainstem have come into the focus of interest in psychiatric and neurological research mainly for two reasons: Firstly, their function is altered early in the course of Alzheimer's disease (AD; Parvizi et al., 2001). Secondly, in a small pilot study the electrical stimulation of the left vagus nerve in the neck by means of an implanted stimulator has shown to improve cognitive impairments in patients with AD (Sjogren et al., 2002).
Methods:
Based on these findings a method for the non-ionvasive measurement of far-field potentials from the vagus nuclei evoked by means of an electrical stimulation via a peripheral branch of the nerve in the outer ear is a potentially interesting diagnostic procedure.
Results:
Vagus Sensory Evoked Potentials (VSEP) can be elicited in a reliable manner in younger and elderly healthy subjects. VSEP-latencies have been found to increase with age in healthy subjects. In a first clinical application, VSEP-latencies in patients with mild to moderate AD were found to be prolonged as compared to age-matched healthy participants.
Conclusions:
This new, none-invasive measure is very easy to apply and may be a disease marker for AD, possibly also in preclinical stages. Further studies are necessary which systematically investigate changes in VSEP measures in patients with neurodegenerative disorders in order to elucidate their diagnostic specifity and validity.
Phenological development and its variation during reproductive growth have important effects on the yield and quality of forage grasses. In perennial ryegrass (Lolium perenne L.) genetic variation in heading date is well recognized, but there are no reliable studies about the variability in the length of the stem elongation phase. To determine the variation in phenological traits of single plants of perennial ryegrass genotypes, a field trial was conducted over three growing seasons (2011–2013) using plant material from eight different ecotype populations, sampled from old permanent grassland swards in Northern Germany. In addition to the phenological stages of jointing, heading and flowering, the critical phase of stem elongation was considered as a new phenological trait. It was hypothesized that the length of the critical phase between jointing and heading differs significantly among genotypes and thus offers a new tool for selecting for specific purposes, e.g. adaption to changing climatic conditions, cutting or grazing as well as yield and quality. The study revealed significant genotypic variation in the observed traits, which was highest for the critical phase (GCV = 0·21). Moderate heritability in jointing (h2 = 0·72) revealed a large environmental impact. In contrast, high heritability (h2 > 0·86) in heading, flowering and the critical phase imply a strong genetic effect. Moderate to high genotypic and phenotypic coefficients of correlation revealed a substantial linkage among the phenological traits. Results are discussed in the context of providing different approaches and strategies in forage crop production, especially with regard to regional weather conditions and future climate change. Significant differences among the tested ecotype populations indicate that existing diversity in permanent grassland can provide source material for further progress in grass breeding.
A considerable expansion of biogas production in Germany, paralleled by a strong increase in maize acreage, has caused growing concern that greenhouse gas (GHG) emissions during crop substrate production might counteract the GHG emission saving potential. Based on a 2-year field trial, a GHG balance was conducted to evaluate the mitigation potential of regionally adapted cropping systems (continuous maize, maize-wheat-Italian ryegrass, perennial ryegrass ley), depending on nitrogen (N) level and N type. Considering the whole production chain, all cropping systems investigated contributed to the mitigation of GHG emissions (6·7–13·3 t CO2 eq/ha), with continuous maize revealing a carbon dioxide (CO2) saving potential of 55–61% compared with a fossil energy mix reference system. The current sustainability thresholds in terms of CO2 savings set by the EU Renewable Energy Directive could be met by all cropping systems (48–76%). Emissions from crop production had the largest impact on the mitigation effect (⩾50%) unless the biogas residue storage was not covered. The comparison of N fertilizer types showed less pronounced differences in GHG mitigation potential, whereas considerable site effects were observed.
As part of a larger evaluation of school nutrition programmes (SNP), the present study examined programme coordinators’ perceptions of strengths, weaknesses, opportunities and threats (SWOT) regarding their SNP and public health professionals’ support.
Design
Qualitative interviews were conducted with twenty-two of eighty-one programme coordinators who had completed a programme evaluation survey. Interviews followed a SWOT framework to evaluate programmes and assessed coordinators’ perceptions regarding current and future partnerships with public health professionals.
Setting
The study was conducted in a large, urban region within Ontario.
Subjects
The twenty-two coordinators who participated represented a cross-section of elementary, secondary, Public and Catholic schools.
Results
SNP varied enormously in foods/services offered, how they offered them and perceived needs. Major strengths included universality, the ability to reach needy students and the provision of social opportunities. Major weaknesses included challenges in forming funding partnerships, lack of volunteers, scheduling and timing issues, and coordinator workload. Common threats to effective SNP delivery included lack of sustainable funding, complexity in tracking programme use and food distribution, unreliable help from school staff, and conflicts with school administration. Opportunities for increased public health professionals’ assistance included menu planning, nutrition education, expansion of programme food offerings, and help identifying community partners and sustainable funding.
Conclusions
The present research identified opportunities for improving SNP and strategies for building on strengths. Since programmes were so diverse, tailored strategies are needed. Public health professionals can play a major role through supporting menu planning, food safety training, access to healthy foods, curriculum planning and by building community partnerships.
Systematic field exploration in Tennessee has located a wealth of new rock art—some deep in caves, some in the open air. The authors show that these have a different repertoire and use of colour, and a different distribution in the landscape—the open sites up high and the caves down low. The landscape has been reorganised on cosmological terms by the pre-Columbian societies. This research offers an exemplary rationale for reading rock art beyond the image and the site.
The expansion of biogas production in Germany poses a challenge in terms of the production of substrates for co-fermentation and the efficient use of biogas residues as fertilizers. At present there is limited information on the fertilizer value of biogas residues from energy-cropping systems. A 2-year field experiment was conducted at two sites in northern Germany to quantify the yield, nitrogen (N) concentration and the N balance of maize (Zea mays L.) grown in different crop rotations: (i) maize monoculture (R1), (ii) maize – whole-crop wheat followed by Italian ryegrass as catch crop (R2) and (iii) maize – grain wheat followed by mustard as catch crop (R3). Crops were fertilized with different levels of biogas residues, cattle slurry, pig slurry, or mineral N fertilizer, which allowed quantification of the apparent N recovery (ANR) of the fertilizer types tested. The results revealed that crop rotation in interaction with N amount had a pronounced effect on the yield of maize. Maximum yield of 19·1 t dry matter (DM)/ha, corresponding to biogas production of 6685 m3N CH4/ha, was achieved in maize monoculture on a sandy loam site. Maize grown in R3 showed the lowest N response but had the highest yield under low N supply, whereas R2 generally had the lowest yield and N content. Differences in yield performance were reflected in the N balances, differing by 50 kg N/ha between R1 and R2, whereas R3 produced the lowest yield at low N supply. The carry-over effects from the preceding catch crops in R2 and R3, however, reduce the meaningfulness of the simple N balance. Nitrogen fertilizer type showed no interaction with crop rotation. Biogas residue application resulted in similar maize yielding performance to pig slurry and cattle slurry. However, relative N fertilizer value (RNFV) was 30% higher for biogas residue at optimal N supply, i.e. the minimum N input to achieve maximum DM yield.
Using the extended Hertzian approach (EHA), the “effectively shaped indenter” corresponding to Pharr's concept is described in terms of a parameter set {d0,d2,d4,d6}, which can be determined by a fitting procedure from the unloading curve of an indentation experiment. Owing to the limited accuracy of measurement, a given experimental curve may in principle correspond to more than one such parameter set. Based on indentation experiments with a Berkovich indenter into fused silica, we have investigated the influence of the fitting procedure itself on the results. We suggest a certain manual fitting procedure, which delivered a yield strength Y = (7.1 ± 0.1) GPa independent of the maximum load. Manual fitting always includes some degree of subjectivity, however, both Y and the elastic field as a whole proved to be relatively robust against modifications of the parameter set. We also suggest a preliminary objective procedure, which delivered Y = 6.8 − 7.1 GPa. In addition, we have performed finite element method (FEM) simulations of elastic–plastic indentations of a conical indenter into a von Mises solid with a yield strength of Y = 7.0 GPa. The simulated unloading curve was analyzed using the EHA in the same manner as the experimental curves, and yield strength of 6.95 GPa was obtained being very close to the input value of the FEM.
The possibility of analyzing surfaces at the nanoscale provided by
atomic force microscopy [1] (AFM) has been explored for various
materials, including polymers [2], biological materials [3] and clays
[4]. Further uses of AFMs involved nanomanipulation [5] and measurements
of interaction forces, where the latter has been referred to as atomic
force spectroscopy (AFS) [6]. Measurements of surface-surface
interactions at the nanoscale are important because many materials have
their properties changed at this range [7]. For samples in air, the
interactions with the tip are a superimposition of van der Waals,
electrostatic and capillary forces. A number of surface features can now
be monitored with AFS, such as adsorption processes and contamination
from the environment. Many implications exist for soil sciences and
other areas, because quantitative knowledge of particle adhesion is
vital for understanding technological processes, including particle
aggregation in mineral processing, quality of ceramics and adhesives. In
this paper, we employ AFS to measure adhesion (pull-off force) between
the AFM tip and two types of substrate. Adhesion maps are used to
illustrate sample regions that had been contaminated with organic
compounds.
The dynamics of dry granular flows down a vertical glass pipe of small diameter have
been studied experimentally. Simultaneous measurements of pressure profiles, air and
grain flow rates and volume fractions of particles have been realized together with
spatio-temporal diagrams of the grain distribution down the tube. At large grain flow
rates, one observes a stationary flow characterized by high particle velocities, low
particle fractions and a downflow of air resulting in an underpressure in the upper
part of the pipe. A simple model assuming a free fall of the particles slowed down by
air friction and taking into account finite particle fraction effects through Richardson–Zaki's
law has been developed: it reproduces pressure and particle fraction variations
with distance and estimates friction forces with the wall. At lower flow rates, sequences
of high-density plugs separated by low-density bubbles moving down at a constant
velocity are observed. The pressure is larger than outside the tube and its gradient
reflects closely the weight of the grains. Writing mass and momentum conservation
equations for the air and for the grains allows one to estimate the wall friction, which
is less than 10% of the weight for grains with a clean smooth surface but up to
30% for grains with a rougher surface. At lower flow rates, oscillating-wave regimes
resulting in large pressure fluctuations are observed and their frequency is predicted.
The resurrection plant Myrothamnus flabellifolia has the ability to recover from repeated prolonged and extreme
desiccation cycles. During the dry state the inner walls of the xylem vessels seemed to be covered, at least partly,
by a lipid film as shown by Sudan III and Nile Red staining. The lipid film apparently functioned as an ‘internal
cuticle’ which prevented the adjacent parenchyma ray cells from complete water loss. The hydrophobic nature of
the inner xylem walls was supported by the finding that benzene ascended as rapidly as water in the xylem of dry
Myrothamnus branches. On watering, numerous lipid bodies were found in the water-conducting vessels,
presumably formed from the lipid film and/or from lipids excreted from the adjacent living cells into the vessels.
The presence of lipid bodies within the vessels, as well as the hydrophobic properties of the inner xylem walls,
could explain the finding that the xylem pressure of hydrated, well watered plants (measured both under
laboratory and field conditions with the xylem pressure probe) never dropped below c. −0.3 MPa and that
cavitation occurred frequently at low negative xylem pressure values (−0.05 to −0.15 MPa). The xylem pressure
of M. flabellifolia responded rapidly and strongly to changes in relative humidity and temperature, but less
obviously to changes in irradiance (which varied between 10 and c. 4000 μmol m m−2 s−1). The morphological position
of the stomata in the leaves could explain the extremely weak and slow response of the xylem pressure of this
resurrection plant to illumination changes. Stomata were most abundant in the furrows, and were thus protected
from direct sunlight. Simultaneous measurements of the cell turgor pressure in the leaf epidermal cells (made by
using the cell turgor pressure probe) revealed that the xylem and the cell turgor pressure dropped in a ratio of 1:0.7
on changes in the environmental parameters, indicating a quite close hydraulic connection and, thus, water
equilibrium between the xylem and cellular compartments. An increase in irradiance of c. 700 μmol m−2 s−1
resulted in a turgor pressure decrease from 0.63 to 0.48 MPa. Correspondingly, the cell osmotic pressure increased
from 1.03 to 1.22 MPa. From these values and by assuming water equilibrium, the osmotic pressure of the xylem
sap was estimated to be 0.25–0.4 MPa. This value seems to be fairly high but may, however, be explained by the
reduction of the water volume within the vessels due to the floating lipid bodies.
Homogeneously developed oak (Quercus robur L.) microcuttings
were challenged in a Petri-dish system with the
mycobionts Piloderma croceum J. Erikss. & Hjortst. and
Paxillus involutus (Batsch) Fr. Non-destructive
observations over 10 wk followed by d. wt measurements at the end of the
assays served to precisely characterize
root and shoot development, dynamics of mycorrhizal colonization and
morphological ratio. In the system, plant
development, and especially root morphogenesis, had more similarities to
those of stump cuttings or of older
seedlings than to those of 3-month-old seedlings. Whereas Paxillus
involutus displayed early mycorrhizal
colonization and had no significant morphological effects on the host
Piloderma croceum modified markedly the
entire plant development before a delayed mycorrhiza formation. The latter
mycobiont stimulated elongation and
production of the lateral root system and also increased the leaf surface.
However, no corresponding weight
increases were noted, which was reflected by significant increase of both
specific root length and specific leaf area.
These differential effects are discussed in relation to data concerning
carbon
requirement and auxin production
of the mycobionts. The developed system was shown to be highly suitable
for comparative studies with diverse
mycobionts on recognition and physiological balance between partners before,
and in the early stage of, formation of mycorrhizas.
We implanted at 300 eV into Cu-chalcopyrite semiconductors at temperatures between 50°C and 300°C. The surface chemistry is similar to the previously reported behavior of CuInS2 implanted with a H2+, H+ low energy ion beam [1] with respect to secondary phase etching. We also found an increase of radiative recombination (photoluminescence), which had been attributed to defect passivation and, hence, as an indicator of hydrogen incorporation [2]. Under the 300 eV implantation conditions, however, we observed neither a hydrogen concentration in a few hundred nm surface range exceeding the NRA detection limit of about 1×1019 cm-3 nor a pronounced stoichiometry variation in the ternary material, as proved by Raman measurements.
We conclude, therefore, that a 300 eV implantation introduces significantly less atomic hydrogen into the volume of the sample than previously reported for other beam compositions under similar temperature and current density conditions. This could be a result of the very low energy of less than 100 eV which can be expected for atomic H produced by dissociation of 300 eV at the surface, making the instant out-diffusion into the high vacuum of the implantation chamber a favored process.
Thermal Rossby waves driven by centrifugal buoyancy in a
rotating cylindrical fluid
gap become unstable right at the onset of convection when the Prandtl number
is small. The Benjamin–Feir–Newell instability leads
to modulated thermal Rossby
waves which can also be described by a generalized Ginzburg–Landau
equation. A
resonance instability occurs at a finite distance in
Rayleigh number from the neutral
curve. It leads to two independent wave patterns propagating past each
other and
finally gives rise to vacillations of the amplitude of convection. Most
of these features
can be described to a good approximation by a system of three coupled amplitude
equations. Time integrations based on a Galerkin expansion show transitions
to
chaotic convection at higher Rayleigh numbers.
This commentary cites several findings of neuromuscular
research that are consistent with aspects of Plamondon's
kinematic theory. In addition, we point out certain biomechanical
properties of the limb that influence the requirements for the
production of accurate movement, and might thus compromise
the global applicability of any law governing speed/accuracy
trade-offs.
Siliconoxynitride layers with thicknesses between 5 and 10 nm were grown on (100) oriented silicon by rapid thermal processing (RTP) using either N2O or NH3 as nitridant. In order to study the trapping behaviour at the interface and in the insulator bulk, capacitance-voltage (CV) and current-voltage (IV) measurements have been performed combined with different magnitudes of Fowler-Nordheim stress. In addition, Deep Level Transient Spectroscopy (DLTS) has been applied for interface state detection. Auger Electron Spectroscopy (AES) has been used to obtain depth profiles for Si, N, O and C. The deconvolution of the AES signal displays significant peak contributions related to intermedium oxidation states. Nuclear Reaction Analysis (NRA) was successfully applied for hydrogen detection in buried SiOxNy thin films.